1. Field of the Invention
The present invention is directed to an electrohydraulic fluid monitor system for detecting malfunctions in an electrohydraulic fluid system and, more particularly, an apparatus and method for monitoring the electrohydraulic fluid, reservoir, motor pump, accumulators and drain line in an electrohydraulic fluid system to detect malfunctions therein.
2. Description of the Related Art
An electrohydraulic fluid system can be used, for example, to operate steam valves in a steam turbine. An example of such an electrohydraulic fluid system is manufactured by Westinghouse and described in IL 1250-3713(1/69) and IL 1250-3713A (7/88) published by Westinghouse. The electrohydraulic fluid system controls the steam valves using high pressure electrohydraulic fluid. FIG. 1 illustrates such an electrohydraulic fluid system, further provided with sensors which will be described, presently. In FIG. 1, electrohydraulic fluid is supplied along electrohydraulic fluid line 1. The electrohydraulic fluid is pumped from the reservoir 2 to steam valves by one of the motor pumps 4 and 6 along the electrohydraulic fluid line 1. One of the motor pumps 4 or 6 operates at a time, while the other is provided as a standby. Each of the motor pumps 4 and 6 have a conventional motor, one of which operates continuously, either driving a conventional pump to pump up pressure in the system (loading) or idling (unloading), during which time the pressure drops. An electrohydraulic control unit 8 is positioned along the electrohydraulic fluid line 1 to control the pressure therein. The control block includes unloader valves, which are conventional pressure valves which open and close to maintain the pressure at a specified range. The unloader valves either divert oil to charge the system or divert it back to the reservoir. Accumulators 10 maintain the pressure in the electrohydraulic fluid line 1. The electrohydraulic fluid is supplied to steam valve hydraulic actuators to actuate steam valves 12 which control steam flow to a steam turbine (not pictured). The electrohydraulic fluid is returned to the reservoir 2 along drain line 13.
An electrohydraulic fluid system such as the one discussed above may serve a very important function, such as in the operation of the steam valves in a steam turbine, as described. For this reason, it is essential that malfunctions in the electrohydraulic system can be detected or diagnosed as quickly as possible.